Problem: Simplify the following expression: $a = \dfrac{-49n + 21}{7n}$ You can assume $n \neq 0$.
Explanation: Find the greatest common factor of the numerator and denominator. The numerator can be factored: $-49n + 21 = - (7\cdot7 \cdot n) + (3\cdot7)$ The denominator can be factored: $7n = (7 \cdot n)$ The greatest common factor of all the terms is $7$ Factoring out $7$ gives us: $a = \dfrac{(7)(-7n + 3)}{(7)(n)}$ Dividing both the numerator and denominator by $7$ gives: $a = \dfrac{-7n + 3}{n}$